Ejector type refrigerating system



Oct; 10, 1939.

L. B. MILLER Er AL EJECTOR TYPE REFRIGERATING SYSTEM Original Filed Sept. 10, 1934 .9 NJ fvzvemtvrs 1190B. Miller JirmgFDewr Patented Oct. '10, 1939 UNITED STATES PATENT OFFlCE EJECTOR TYPE REFRIGERATING SYSTEM Original application September 10, 1934, Serial No. 743,408. Divided and this application November 20, 1935, Serial No. 50,690

i 14 Claims.

This invention relates to refrigerating systems or cooling systems, utilizing a steam jet ejector for performing the cooling action. This application is a division of our copending application Ser. No. 743,408, filed September 10, 1934, which has matured into Patent 2,143,356, dated January 10, 1939.

It is an object of this invention to provide a control system for a steam jet ejector refrigerating mechanism whereby the operation of the refrigerating mechanism is accurately controlled and whereby the operation thereof is maintained safe at all times.

It is an object of this invention to provide a control system for a steam jet ejector refrigerator mechanism wherein the ejector is controlled in accordance with steam pressures and condenser vacuum.

Another. object of this invention is to provide a control system for a refrigerating mechanism of the class described wherein the boiler for supplying steam to the refrigerating mechanism is placed in operation in response to changes in the condition to be'controlled and in response to the chilled water or evaporator temperature and wherein the ejector is placed in operation in response to the steam pressure developed by the boiler and the Vacuum in the condenser.

Still another object of this invention is to provide a control system for a steam jet ejector re frigerating mechanism wherein the boiler for supplying steam to the refrigerating mechanism is placed in operation in response to a demand for cooling and the chilled water temperature, wherein the secondary ejectors and the vacuum pump are placed in operation when the boiler steam pressure rises to a predetermined value and wherein the primary ejector is placed in operation when a predetermined vacuum has been produced in the condensers and when the boiler steam pressure has reached a predetermined higher value.

Other objects and advantages will become apparent. to those skilled in the art upon reference to the accompanying specification, claims and drawing, in ,which drawing is diagrammatically illustrated our invention as applied to a steam jet ejector refrigerating mechanism.

An evaporator wherein the cooling fluid is cooled is designated at 10. .Cooling fluid which may take the form of chilled water is drawn from the evaporator 10 through a pipe II by a circulrtting pump l2. The chilled water is then circulated through a coolingcoil l3 which may be located in a conditioning chamber I4 and conveyed by a pipe IE to a spray l6 located within the evaporator I 0. A vacuum is maintained in the evaporator ID by means of a primary ejector I! which connects into a primary condenser I8. The secondary condenser is provided with secondary ejectors 2| and 22 for assisting in the production of a vacuum in the condensers l8 and 20 and for purging air and other non-condensible gases from the condensers l8 and 20.

The primary ejector I1. is provided with steam through a pipe 23 connected into a steam header 24 which in turn connects into a boiler 25. The

' flow of steam through the pipe 23 to the primary ejector I1 is controlled by means of a primary steam valve 26 which ismoved to an open or closed position by means of amotor, 'means 21. Steam is supplied to the secondary ejectors 2| and 22 by means of pipes 28 and 29 connecting into the pipe 23 ahead of primary steam valve 26. The supply of steam to the secondary ejectors 2| and 22 is controlled by a secondary steam valve 30 which is moved to an open or closed position by means of a motor means 3|.

Condensed steam is drawn from the condenser l8 through a pipe l9 by means of a vacuum pump 33. A suitable drain or outlet for exhausting the secondary condenser, is indicated by the reference character 34. The vacuum pump 33 returns the condensate to the boiler 25. For purposes of illustration in this application, the boiler is shown to be of the gas-fired type. the gas being supplied to the boiler through a gas pipe 35 under the control of a gas valve 36 which is moved to open or closed position by means of a motor means 31.

Condensing fluid is conveyed from some source, not shown, through a pipe 39 to the primary condenser [8 under the control of a valve 40 which is moved to open or closed position by means of a motor 4|. The used condensing fluid is conveyed away from the primary condenser [8 through a pipe 42. The secondary condenser 29 is connected by pipes 43 and 44 with the condensing water pipes 39 and 42,- respectively, whereby condensing fluid is supplied likewise to the secondary condenser 20 when the valve 40 is moved to an open position. In case a cooling tower is utilized for cooling the condensing fluid, the pipes 39 and 42 may extend to a cooling tower, not shown, and

under such circumstances, it is desirable to have forced circulation of the condensing fluid. The

circulating pump, not shown, may be placed in the pipe 39 and the arrangement may be such that when the valve 40 is open, the circulating pump is placed in operation.

A control device, responsive to the condition to be controlled, is designated generally at 46 and for purposes of illustration in this application, it is shown to comprise a thermostatic element 41 for operating a switch arm 48 with respect to a contact 49, the arrangement being such that upon an increase in temperature affecting the bimetallic element 41, the switch arm 48 is moved in the direction of the arrow indicated by H into engagement with the contact 49. Preferably, such engagement is made when the temperature increases to 75 F.

A low limit control is generally designated at 50 and may comprise a bellows connected by a pipe 52 to the steam header 24. The bellows 5i operates a pivoted lever 53 which carries a mercury switch 54, the arrangement being such that when the boiler pressure decreases to 2 pounds, the mercury switch 54 is moved to a circuit making position as shown in the drawing. This invention also contemplates the use of a high limit control generally designated at 55 and which may comprise a bellows 56 connected by a pipe '51 to the steam header 24. The bellows 56 operates a pivoted lever 58 which carries a mercury switch 59, the arrangement being such that when the boiler pressure increases to 14 lbs., the mercury switch 59 is tilted to a circuit breaking position.

A pressure responsive device generally designated at 60 may comprise a bellows 6| connected -by a pipe 62 to the steam header 24.

This bellows 6| may operatea pivoted lever 63 which carries a double-ended mercury switch 64.. Upon an increase in boiler pressure to 9 lbs., the

in the drawing to make contact between theright-hand contacts. The pressure responsive device 60 is adapted to control the energization of a relaycoil 65, the arrangement being such that when the relay coil 65 is energized, a switch arm 66 is moved into engagement with contact The boiler 25 is provided with a low water cutoff mechanism generally designated at 68 which is adapted to operate a mercury switch 69 to a circuit-breaking position when the level of the boiler water becomes abnormally low. A vacuum responsive device is designated generally at TI] and comprises a bellows ll connected by a pipe (2 into the secondary condenser 29. The bellows H operates a pivoted lever 73 which carries a double-ended mercury switch it, the arrangement being such that when the vacuum in the secondary condenser 20 reaches 16 inches of mercury, the switch is tilted from the position shown in the drawing to a position wherein contact is made between the right contacts thereof. Another pressure-responsive device is generally designated at 15 and comprises a bellows l5 connected into the steam pipe 25 by means of a pipe H. The bellows 16 operates a pivoted lever 78 which carries a double-ended mercury switch 19. When the boiler pressure increases to 12 lbs., the mercury switch 19 is tilted to a position opposite that shown in the drawing to make contact between the left contacts and when the boiler pressure decreases to 11 lbs., the mercury switch is returned to the position shown in the drawing to make contact between the right contacts.

A temperature responsive device is generally ture to .a value of say, 35 F., the mercury switch 85 is moved to a circuit-breaking position.

This invention contemplates the use of a relay coil 86 which when energized moves a switch arm 81 into engagement with a contact 88. Line wires for supplying power to the control system of our invention are designated at 90 and 9|.

When the boiler pressure decreases to 2 lbs.

so as to move the mercury switch 54 to a circuitmaking position, a circuit is completed from the line wire 90 through wires 92 and 93, mercury switch 54 of the low limit control 50, wires 91 and 98, mercury switch 69 of the low water out 01f 68, wire 99, mercury switch 85 of the evaporator temperature responsive device 80, wire I09, motor 31, and wire l0! back to the other line wire 9|. Completion of this circuit causes energization of the motor 31 and consequent opening of the gas valve 36 whereby the boiler 25 is energized to generate steam. When the steam pressure has been restored to 2 lbs., the mercury switch 54 is moved to a circuit-breaking position to break the above circuit to close the valve 36 to prevent the further generation of steam. In this manner, steam at 2 lbs., may be maintained within the boiler 25. Since the low water cut-off mechanism is included in this circuit, the boiler 25 may not be energized if the boiler water is abnormally 'low. Also, if 'the evaporator temperature is down to whereby further cooling is not needed, operation of the boiler 25 is prevented since the mercury switch 85 included in of the high limit control 55, wires H04 and 99,'

mercury switch 69 of the low water out off device 68, wire 99, mercury switch 85 of the evaporator temperature responsive device 89, wire m9, valve motor 31 and wire llll back to the other line wire 91!. Therefore upon a call for cooling, the valve motor 31 is energized to open the gas valve 36 to cause operation of the boiler 25 to generate steam therein. Since the above-referred to citcuit includes the high limit control 55 which is moved to a circuit-breaking position upon the occurrence of 14 lbs. steam pressure within the boiler 25, the occurrence of dangerous pressures within the boiler 25 is prevented. Likewise, the valve 36 is prevented from being opened when the boiler water level is abnormally low or when the evaporator temperature is abnormally low by means of the low Water cut-ofi device 63 and the evaporator temperature responsive device 80. In this manner, safe operation of the boiler 25 is insurfed.

When the boiler pressure has increased to 9 lbs., due to the operation of-the boiler in the above-referred to manner, the mercury switch 64 of the pressure responsive device 60 is moved to currence of 9 lbs. steam pressure to a position opa position opposite to that shown in the drawing to complete a circuit from the line wire 90 hrough wire I06, left contacts of mercury switch 64, wires I01, I08 and I09, secondary valve motor 3| and wires I I0 and III back to the other line wire 9| Completion of this circuit causes opening of the valve 30 to supply steam to the secondary ejectors 2| and 22. When the boiler pressure decreases to a value lower than 9 lbs., say 7 lbs., the mercury switch 64 is returned to the position shown in the drawing to complete a circuit from the line wire 90, through wire I06, right contacts of mercury switch 64, wires H2 and H3, thesecondary valve motor 3| and wires H0 and III back to the other line wire 9|. Completion of this circuit causes operation of the valve motor 3| to move the valve 30 to a closed position to prevent the further supply of steam to the secondary ejectors 2| and 22. In this manner, the secondary ejectors 2| and 22 are controlled directly in response to a predetermined boiler steam pressure.

Movement of mercuryswitch 64 to the position opposite to that shown in the drawing completes a circuit also from the line wire 90, through wire I06, mercury switch 64, wires I01 and H4, relay coil 65 and wire H5 back to the other line wire 9|. Completion of this circuit at 9 lbs. steam pressure causes energization of the relay coil 65 to move the switch arm 66 into engagement with the contact 61. Movement of switch arm 66 into engagement with the contact 61 completes a circuit from the line wire 90, through wire H6, contact 6I, switch arm 66, wire II I, electrically operated vacuum pump .33 and wire H8 back to the other line wire 9|. Completion of this circuit causes operation of the electrically operated vacuum pump 33 which combines its action with that of the secondary ejectors 2| and 22 to produce a vacuum in the primary and secondary condensers I8 and 20. When the boiler pressure decreases below 9 lbs., the circuit through the relay coil is broken and the relay coil 65 is therefore deenergized to move the switch arm 66 out of engagement with the contact 67 to prevent the further operation of the vacuum pump 33.

Movement of the mercury switch 64 by the ocposite to that shown in the drawing completes another circuit from the line wire 90, through wire I06, mercury switch 64, wires I01, I08 and H9, valve motor 4| and wires I20 and III back to the other line wire 9|. Completion of this circuit causes operation of the valve motor 4| to move the valve 40 to an open position whereby condensing fluid is delivered to the primary and secondary condensers I8 and 20. When the boilersteam pressure drops below 9 lbs., a circuit is completed from the line wire 90, through wire I 06, mercury switch 64, wires I I2 and I2 I, valve motor 4| and wires I20 and I II back to the other line wire 9|. Completion of this circuit causes operation of the valve motor 4| to move the valve 40 to a closed position to prevent the further supply of condensing fluid to the primary and secondary condensers I8 and 20. In case a circulating pump is used, the pump may be placed in operation in the same manner that the valve 40 is opened, that is, the pump may be placed in operation when the steam pressure rises above 9 lbs., and may be placed out of operation when the steam pressure drops below 9 lbs.

From the above it is seen that when the boiler pressure reaches a predetermined value illustrated as 9 lbs., the secondary ejectors 2| and 22,

the vacuum pump 33 is placed in operation and the valve 40 is opened to supply condensing Water to the primary and secondary condensers I8 and 20. When the boiler pressure decreases below this predetermined value, to' say 7 lbs., as illus trated, the secondary steam valve 30 is closed to prevent the further operation of the secondary ejectors 2| and 22, the vacuum pump 33 is stopped and the valve 40 is closed to prevent the further circulation of condensing fluid through the condensers I8 and 20.

When a predetermined vacuum has been produced in the condensers I8 and 20 by the action of the secondary ejectors 2| and 22 and the vacuum pump 33, the mercury switch I4 of the vacuum responsive device I0 is moved to a position opposite that shown in the drawing. Tilting of the mercury switch in this manner is preferably made at a vacuum of 16 inches of mercury. When the boiler steam pressure rises to a predetermined higher value, say 12 lbs., the mercury switch III of the pressure responsive device I5 is'tilted to a position opposite to that shown in the drawing. Tilting of the mercury switches I4 and I9 in this manner in response to a predetermined high boiler pressure and a predetermined vacuum within the condensers I 8 and 20 completes a circuit from the line wire 90, through wires I23 and I24, mercury switch I4, wire I25, mercury switch I9, wires I26 and I21, primary valve motor 21 and wire I28 back to the other line wire 9|. Completion of this circuit causes operation of the valve motor 21 to open the valve 26 to supply steam to the primary ejector II.

If the vacuum in the secondary condenser 20 should fall below 16 inches of mercury, the mercury switch I4 is returned to the position shown in the drawing to break the above-referred to circuit and to complete a circuit from the line wire 90, through wires I23 and I 24, mercury switch 14, wires I29 and I30, primary valve motor 21 and wire I28 back to the other line wire 9|. Completion of this circuit causes operation of the valve motor 21 to move the valve 26 to a closed position to prevent the further supply of steam to the primary ejector I I. In a like manner, if

the steam pressure should fall below 12 lbs., so

as to tilt the mercury switch I9 to the position shown in the drawing, a circuit is completed from the line wire 90, through wires I23 and I3 I, mercury switch I9, wires I32 and I30, valve motor 2! and wire I28 back to the other line wire 9|. Completion of this circuit causes operation of the valve motor 21 to move the valve 26 to a closed position. Therefore, it is seen that the primary ejector IIis placed in operation only when there is sufiicient steam pressure to insure the proper operation thereof and when there is a predetermined vacuum existing within the condensers I8 and 20. Therefore, the primary ejector II is not allowed to operate if unfavorable conditions are present which would prevent the satisfactory operation thereof.

Movement of switches 14 and I9 to. the positions opposite to those shown upon the occurrence of a predetermined vacuum and a predetermined steam pressure also causes completion of a circuit from the line wire 90, through wires I23 and I24, mercury switch I4, wire I25, mercury switch I9, wires I26 and I34, relay coil 06 and wires I35 and I28 back to the other line wire 9|. Completion of this circuit causes energization of relay coil 86 to move the switch arm 81 into engagement with the contact 88. This causes completion of a circuit from the line wire 90, through [III wire I36, contact 88, switch arm 81, wire I31, electrically operated circulating pump l2 for the chilled water and wire I38 back to the other line wire 9|. This causes operation of the circulating pump I 2 to supply chilled water to the cooling coil l3 located in the conditioning unit l4. If either of mercury switches 14 or 19 are moved to the position shown in the drawing as the result of a decrease in condenser vacuum or a decrease in steam pressure, the circuit through the relay coil 86 is broken whereby the switch arm 81 is moved out of engagement with the contact 86 to stop the further operation of the circulating pump .12.

Summarizing the operation of the, complete controlsystem, the boiler steam pressure may or may not be maintained at a predetermined minimum value depending upon whether or not the pressure switch ifl is used. Upon a call for cooling by the condition responsive device 46, the boiler 25 is placed in operation'to generate steam subject to the operation of the high limit control 55, the low water cut-off control 68 and the evaporator temperature controller 86. In this manner, the boiler 25 is placed in operation upon a demand for cooling and this operation is safeguarded with respect to abnormally high steam pressures and low water level and the boiler is also prevented from operating in case the evapo rator temperature. should become so low as to cause freezing of the refrigerating mechanism. When the boiler pressure rises to a predetermined value of 9 lbs., the pressure responsive device 60 places the secondary ejectors 2| and 22 in operationQplaces the vacuum pump 33 in operation, and also causes circulation of condensing-water through primary and secondary condensers I8 and 26 by either opening the valve 40 or by placing the circulating pump, not shown, in operation. Therefore, at ,some intermediate steam pressure, the refrigerating mechanism is placed in condition for operation and in case the steam pressure drops below this intermediate value, the secondary ejectors 2| and 22, the vacuum pump 33 and the condensing water circulating means are rendered inoperative. When the boiler pressure increases to a-higher value of 12 lbs., and when the vacuum within the condensers l8 and 20 is brought to a predetermined minimum value of 16 inches of mercury, the primary steam valve 26 is opened to allow operation of the primary ejector H to create a vacuum in the evaporator l6 whereby the cooling process map be carried out and to increase the vacuum in the condenser above the predetermined minimum value of 16 inches of mercury. .The circulating pump l2 for circulating the chilled water is placed inoperation simultaneously with the placing in operation of the primary ejector l1 whereby the chilled water is immediately circulated to the cooling coil l3 located in the conditioning unit H. In case the steam pressure should drop below 12 lbs., and/or the vacuum should decrease below 16 inches ofmercury, the primary ejector I1 and the chilled water circulating pump l2 will be rendered inoperative. When the thermostat 46 is satisfied so as to no longer demand cooling,.the firing means for the boiler 25 is stopped and the boiler pressure decreases causing shutting down of the refrigerating mechanism.-

Although for purposes of illustration, we have used definite pressure and temperature values, other pressure and temperature values may be used and such is within the contemplation of this invention. By reason of the above control system,

an accurate and safe control of a steam jet ejector type refrigerating mechanism is obtained. Although we have disclosed one form of our invention for purposes of illustration, other forms thereof may become apparent to those skilled in the art and consequently, this invention is to be limited only by the scope of the appended claims and prior art.

We claim as our invention:

1. In a steam jet ejector cooling device including primary and secondary ejectors, a boiler for supplying steam to said ejectors, a primary valve in control of the flow of steam to the primary ejector and a secondary valve in control of the supply of steam to the secondary ejector, the combination of means responsive to a demand for operation of the cooling device and operative to place said boiler in operation, and pressure responsive means responsive to boiler pressure operative to open the secondary valve at a first boiler pressure, to open the primary valve at a higher second boiler pressure, and to render the boiler inactiveat a higher third boiler pressure;

2. In a cooling system having a cooling coil for cooling a space, a steam operated cooling mechanism including a condenser, an evaporator and primary and secondary ejectors for supplying chilled fluid to the cooling coil, the combination of means in control of the circulation of chilled fluid to the cooling coil, a condensate pump for the cooling mechanism, a valve in control of the condenser water for the cooling mechanism, a boiler for supplying steam to said ejectors, a primary valve in control of the flow of steam to the primary ejector, asecondary valve in control of the supply of steam for the secondary ejector, a thermostat responsive to the temperature of the space operative to place said boiler in operation upon a demand for cooling, and means responsive to boiler pressure to open the secondary valve and condenser water valve and to operate the condensate pump at a low boiler pressure, to open the primary valve and operate the circulation controlling means at an intermediate boiler pressure, and to render the boiler inoperative at a high boiler pressure.

' 3. In a cooling system having a cooling coil for cooling a space, a steam operated cooling means including a condenser, an evaporator and primary and secondary ejectors for supplying chilled fluid to'the cooling coil, the combination of means in control of the circulation of chilled fluid to the cooling coil, a condensate pump for'the cooling means, a valve in control of the condenser water for the cooling means, a boiler for supplying steam to said ejectors, a primary valve in control of the flow of steam to the primary ejector, a secondary valve in control of the supply of steam to the secondary ejector, a thermostat responsive to the temperature of the space operative to place said boiler in operation upon a demand for cooling, and means responsive to boiler pressure to open the secondary valve and condenser water valve and to operate the condensate pump at a low boiler pressure, and to open the primary valve and operate the circulation controlling means at a higher boiler pressure.

4. In a conditioning system having an evaporator, an ejector therefor, a condenser, and a boiler, the combination of means responsive to a condition to be controlled and to the evaporator temperature for controlling the operation of said boiler, and means responsive to boiler pressure for controlling the operation of the ejector.

5. In a cooling system having an evaporator,

an ejector therefor, a condenser and a boiler, the combination of means responsive to evaporator temperature and boiler pressure for controlling the operation of said boiler and means responsive to boiler pressure and condenser vacum for controlling the ejector.

6. In a cooling system having an evaporator, an ejector therefor, a condenser and a boiler, the combination of means responsive to the temperature to be controlled, evaporator temperature and boiler pressure for controlling the operation of said boiler and means responsive to boiler pressure and condenser vacuum for controlling the ejector.

7. In a conditioning system having an evaporator, an ejector therefor, a condenser and a boiler, the combination of means for controlling the flow of the cooling medium. means for controlling the fiow of the condenser fluid, means for controlling the operation of the ejector, means for controlling the operation of the boiler, means responsive to evaporator temperature and boiler pressure for controlling said boiler control means and said condenser fluid controlling means, and means responsive to condenser vacuum and boiler pressure for controlling said ejector controlling means and said cooling medium flow control means.

8. In a steam jet ejector cooling device including primary and secondary ejectors, a boiler for supplying steam to said ejectors, a primary valve in control of the flow of steam to the primary ejector and a secondary valve in control of the supply of steam to the secondary ejector, the combination of means responsive to a demand for operation of the cooling device and operative to place said boiler in operation, and pressure responsive means responsive to boiler pressure operative to open the secondary valve at a first boiler pressure, and to open the primary valve at a higher second boiler pressure.

9. A control system for a boiler which supplies steam to a steam jet refrigerating apparatus, comprising in combination means for controlling the supply of fuel to the boiler. and means responsive to the evaporator temperature of the steam jet refrigerating apparatus and to a demand for cooling for controlling said fuel controlling means.

10. A control system for a boiler which supplies steam to a steam jet refrigerating apparatus, comprising in combination means for controlling the supply of fuel to the boiler and means responsive to the evaporator temperature of the steam jet refrigerating apparatus, to a demand for cooling and to boiler pressure for controlling said fuel controlling means.

' 11. In a steam operated cooling mechanism including primary and secondary ejectors, a boiler for supplying steam to said ejectors, a primary operation of the primary valve in control of the flow of steam to the primary ejector and a secondary valve in control of the supply of steam to the secondary ejector, the combination of means responsive to the establishment of a condition of low boiler pressure to cause opening of said secondary valve, means responsive to the establishment of an intermediate boiler pressure and a predetermined vacuum in a portion of the cooling mechanism to cause opening of said primary valve, and means responsive to the attainment of a high predetermined boiler pressure to render the boiler inactive.

12. In a steam operated cooling mechanism including primary and secondary electors, a boiler for supplying steam to said ejectors, a primary valve in control of the flow of steam to the primary ejector and a secondary valve in control of the supply of steam to the secondary ejector, the combination of means responsive to the establishment of a condition of low boiler pressure to cause opening of said secondary valve, and means responsive to the establishment of an intermediate boiler pressure and a predetermined vacuum in a portion of the cooling mechanism to cause opening of said primary valve. 1

13. In a conditioning system having an evaporator, primary ejector means associated with the evaporator, a primary condenser connected to said ejector means, a secondary condenser and secondary ejector means arranged to exhaust vapors from the primary condenser and discharge the same into said secondary condenser and to exhaust n on-condensable vapors from said secondary condenser, and a source of steam connected to said ejector means, the combination of means responsive to the pressure of said source of steam for controlling the operation of said secondary ejector means and means responsive to the pressure of said source of steam and the vacuum in said secondary condenser for controlling said primary ejector means.

14. In a conditioning system having an evaporator, primary ejector means associated with the evaporator, a primary condenser connected to said ejector means, a secondary condenser and secondary ejector means arranged to exhaust vapors from the primary condenser and discharge the same into said secondary condenser and to exhaust non-condensable vapors from said secondary condenser, and a boiler, the combination of means responsive to a condition to be controlled and the evaporator temperature for controlling the operation of said boiler, means responsive, to boiler pressure for controlling the operation of said secondary ejector means, and means responsive to the vacuum in one of said condensers and boiler pressure for controlling the ejector means. 

